The Flow Of Gases In Furnaces

268

APPENDIX VII

TABLE IS—Continued

Gas Checker
Air Checker

The heat surface per pass was computed as ..... The corrected value for total heating surface will be : For gas- 3 556X720 =
3 m2 556 2560 m2 00
3 m2 556

For air* 3 556X 1200 = .............

4267 m2 20

The corrected total area of the passes will be: For gas* 0 0162X 720 =
27,558 sq ft 11 m2 664
45,935 sq ft

For air- 0 0162X1200= ..........

19 m244

The corrected average velocity per second of the gases will be : For gas: 21 92-r-ll 664= .................
125. 58 sq ft 1 m 879
209.32sq ft

For air* 31 93-f-19 44 =

1 m 642

For waste gases: 28 05 -r- 11 . 664 ............
6.17ft 2 m 405
5.38ft

38 18-^19 44 =

1 m 964

6.71ft
6.44ft

TABLE 19

Gas on Gas
Air on Air
Gas on Waste Gas
Air on Waste Gas

The heat transfer, total per second,

in calories is. .
1484
2,618
1990
3,516

in B.t.u. is .............
5900
10,400
7900
13,900

Calories per sq m per second .....
0.5797
0.6135
0.7773
0.8239

B.t.u. per sq ft per second .......
0.214
0.226
0.287
0.306

Average temp, differential brick to

gas or gas to brick, C
175°
175°
175°
175°

F. .
315°
315°
315°
315°

Convection factor to still air, ac-
f

cording to curve plotted from

Langmuir's experiments (Fig.

164) is calories per m2 per second
0.294

Correction factor for velocity ==

/35+u
2.516
2.384
2.803
9 ^RQ

\ 35 ...............

u . O\J*j

v — velocity in cm per second.

Convection corrected for velocity:

in calories per m2 per second . . .
0.7397
0.7009
0.8241
0.7553

in B.t.u. per sq ft per second . . .
0.273
0.258
0.304
0.278